The Clinical Research Center for Periodontal Disease (CRCPD), 03 year will conduct studies in three major project areas: 1) The Microbiological Studies Section will continue to define and describe the bacterial flora of defined periodontal disease states and health. 2) The Immunological Studies Section will complete study for polyclonal B-cell activators (PBA) from the prominent gram-negative and gram-positive organisms of the periodontal flora; study the production of osteoclast activating factor (OAF) produced by peripheral blood leukocytes (PBL) in response to PBA and determine the role of cell types in that response; determine the role of monocytes and T-cells in the response of PBL to PBA, extend periods of successful freeze-storage of PBL and use thawed cells for standardized comparisons of blastogenic and PBA responsiveness among subjects with differing periodontal states; study the production of OAF by explants of inflamed gingiva; extend studies of responsiveness to staphylococcal protein among differing periodontal disease states; and study the phenomenon of autologous mixed lymphocyte culture reactions (AMLCR) and the relation of depressed AMLCR to periodontal disease. 3) The PMN Function Studies Section will expand the pool of subjects with severe periodontal defects who have been characterized in polymorphonuclear leukocyte chemotaxis (PMN-CTX) assays; study PMN-cAMP metabolism in those with depressed PMN-CTX compared to normals; pharmacologically dissect cAMP anabolism and catabolism in human PMN; and initiate studies of the human PMN receptors for chemotactic ligands.